Senior Liberal cabinet ministers and MPs with the party engaged in last-minute lobbying efforts outside the Senate chamber Tuesday evening, trying to fend off efforts to amend the government's budget bill.

Finance Minister Bill Morneau, House leader Bardish Chagger and various Liberal MPs pulled aside a number of Senate Liberals and Independent senators on their way into the chamber, hoping to bend their ears before they cast votes on whether to back a Conservative amendment to remove yearly, automatic hikes to the excise duties on alcohol.

"I've never seen this in the eight and half years that I have been here in the Senate: Liberal MPs and ministers hovering in front of the Senate door, and accosting senators. Imagine," Conservative Senator Leo Housakos, chair of the powerful internal economy committee, said in an interview with CBC News.

Some of the MPs stood behind the bar separating the entrance from the Senate floor while the vote was held — an unusual move, as visitors to the chamber usually sit in the gallery above.

MPs do have the right to sit or stand behind the bar but rarely do so in the numbers witnessed Tuesday.

Some Liberal MPs stood behind this bar on the floor of the Senate chamber Tuesday evening as senators voted on whether to accept amendments to the government's budget bill. (Adrian Wyld/Canadian Press)

"I don't know if it was an attempt to intimidate, but it certainly was an attempt to influence the vote," Housakos said.

"Unquestionably, we have the right to amend or even defeat budget bills," Liberal Senate leader Joe Day said Wednesday. "This is a long, long established right, but we know it's always controversial if, and when, we actually exercise that power. But we do have a job and we must not shy away from it."

Another Liberal, Quebec Senator Serge Joyal, appointed by former prime minister Jean Chrétien, said his patience is wearing thin with pressures from the government.

"I keep hearing that we should yield to the other place, well, I'm sorry, the structure of Parliament is one elected body, one unelected. It's the bicameral system."

Joe Day, Liberal Senate leader, says the Red Chamber has every right to amend a budget bill. (CBC)

Housakos said the lobbying Tuesday night speaks to the "discombobulated" nature of the chamber after Trudeau's move to strip partisanship from the Senate by appointing Independents who sit outside the Liberal Party caucus.

"Let's call a spade a spade," Housakos said. "What you have are longtime, traditional Liberals who are saying to Mr. Trudeau, 'You didn't want us in caucus, you didn't want to work with us, why would we back your bill?'"

"There's no cohesion. There's no communication. In the past, you had a line of communication in [national party] caucuses, all of the discussions about the nitty-gritty aspects of these bills would take place there. There's none of that anymore. It's a state of chaos."